Research On Ultrasonic Testing Technology For Fretting Wear Of Electrical Connectors

Electrical connector is the basic electromechanical component to realize the electrical connection and signal transmission between devices,which has been widely used in military and aerospace equipment.Its reliability level has an important impact on the safe and reliable operation of the system.Vibration stress is one of the important factors that affect the reliability of electrical connectors,and continuous mechanical vibration stress will cause fretting wear between the pins and sockets of electrical connectors,resulting in degradation or even failure of contact performance of electrical connectors.Therefore,taking a certain type of the electrical connector as the research object,this paper used ultrasonic testing technology to study the fretting wear between electrical connector contacts under vibration conditions.This paper mainly studied the following contents:Firstly,according to the structural characteristics of contacts,the testing method of wear debris between contacts of electrical connectors was determined,and the relevant ultrasonic testing test scheme was formulated by comparing the differences between different nondestructive testing technologies.Then,the ultrasonic testing device for fretting wear of the electrical connector contacts was designed and related testing platforms were built,mainly including fretting drive unit,ultrasonic testing unit and contact resistance testing unit.The ultrasonic detection unit was designed for the specific requirements of wear debris detection,mainly including fixed rotation unit,mechanical motion scanning unit,ultrasonic signal transmission and acquisition unit,and drive control unit.Finally,the experimental research and analysis were carried out.1)The variation regular of contact debris characteristics under different vibration times,frequencies,accelerations and directions was studied.The results showed that with the increase of vibration times,the amount of debris accumulation and the area of wear were also increase,and the position of debris migrated with the vibration.Among them,the root of the pin produced the most abrasive debris.Compared with the vibration frequency,the vibration acceleration had a greater influence on the accumulation of wear debris and the aggravation of fretting wear,and the characteristic amount of wear debris under Y-direction vibration is about 1.3 times of X-direction and Z-direction.2)The change rule of contact resistance of electrical connector contacts was analyzed.The results showed that the influence rules of vibration times,vibration frequency,vibration acceleration and vibration direction on contact resistance and the wear debris characteristic quantity of contacts were similar.And a grey model was constructed to predict the life of electrical connector contacts.Then,based on the predicted life,it was predicted that when the total amount of abrasive debris reached about 11 mv,the electrical connector would fail.In addition,it could be seen that the contact resistance and wear debris characteristic quantity had extremely high correlation under high vibration frequency and acceleration through correlation analysis by the correlation coefficient analysis.3)The surface morphology(SEM)and energy spectrum analysis(EDS)of the contact pin of the electrical connector were carried out.The results showed that the surface morphology characteristics were basically consistent with the change of wear debris characteristics,which proved that the wear debris characteristic quantity could reflect the wear degree and contact performance degradation of electrical connector contacts to a certain extent.